Frost dates for New Hampton, IA
At New Hampton, the median last spring frost (32°F) is May 2 and the median first fall frost is Oct 5, for a typical growing season of 155 days. For a 90% chance that the last frost has passed, wait until May 14. Nearby ZIP codes are in USDA hardiness zones 4b to 5a.
- May 2Last spring frost (median)50% chance of 32°F after this date
- May 14Safer planting date10% chance of 32°F after this date
- Oct 5First fall frost (median)50% chance of 32°F by this date
- 155 daysGrowing season (median)between 32°F freezes
Last spring frost dates
The chance that the temperature drops to the threshold after each date.
| Temperature | 90% chance later | 50% chance later | 10% chance later |
|---|---|---|---|
| 36°F | Apr 29 | May 10 | May 23 |
| 32°F | Apr 17 | May 2 | May 14 |
| 28°F | Apr 5 | Apr 20 | May 5 |
| 24°F | Mar 29 | Apr 10 | Apr 28 |
First fall frost dates
The chance that the temperature has dropped to the threshold by each date.
| Temperature | 10% chance by | 50% chance by | 90% chance by |
|---|---|---|---|
| 36°F | Sep 16 | Sep 28 | Oct 9 |
| 32°F | Sep 23 | Oct 5 | Oct 18 |
| 28°F | Oct 1 | Oct 15 | Oct 27 |
| 24°F | Oct 11 | Oct 25 | Nov 6 |
Growing season length
Days between the last spring and first fall freeze, as the length reached in 9, 5 and 1 out of 10 years.
| Temperature | 9 in 10 years at least | 5 in 10 years at least | 1 in 10 years at least |
|---|---|---|---|
| 36°F | 121 days | 139 days | 155 days |
| 32°F | 137 days | 155 days | 173 days |
| 28°F | 155 days | 175 days | 194 days |
| 24°F | 176 days | 196 days | 215 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 50659 | 5a | -20 to -15°F | 6 km |
| 50645 | 5a | -20 to -15°F | 11 km |
| 50630 | 5a | -20 to -15°F | 13 km |
| 52154 | 5a | -20 to -15°F | 14 km |
| 50603 | 5a | -20 to -15°F | 20 km |
| 52171 | 5a | -20 to -15°F | 21 km |
| 50628 | 4b | -25 to -20°F | 26 km |
Not the official USDA Plant Hardiness Zone Map. Zones shown here are the values published in the USDA-ARS / Oregon State University PRISM Group 2023 ZIP code tables, shown unaltered. For the official interactive map, visit planthardiness.ars.usda.gov.
About this station
- NOAA station ID USC00135952, at 43.0453, -92.3122, elevation 350 m (1,148 ft).
- Data quality: Standard (24+ years of data), 29 years of freeze data.
- Average days per year at or below 32°F: 158.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Tripoli (26 km)
- Charles City (29 km)
- Cresco 1 NE (42 km)
- Fayette (43 km)
- Osage (48 km)
- Decorah (51 km)
- Allison (51 km)
- Oelwein 1e (54 km)
Sources
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020, annual/seasonal normals by station (version 1.0.1), file dated June 27, 2023; documentation.
- USDA Agricultural Research Service and PRISM Group, Oregon State University, 2023 Plant Hardiness Zone Map ZIP code tables (CONUS, Alaska, Hawaii, Puerto Rico), files dated November 17, 2023. Data © PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed November 1, 2026. Official map: planthardiness.ars.usda.gov.
- U.S. Census Bureau, 2024 Gazetteer ZIP Code Tabulation Areas file, dated August 30, 2024 (ZIP centroids used to find the nearest station).
Freeze dates are 30-year probabilities, not forecasts. Check your local forecast before planting tender plants.